Mystery Damp - Thoughts?

[kernowqueen]

We moved into this house 2 years ago and there was damp in this corner of the living room. This is an internal wall butting against the front facade of the house. The damp appears right in the corner. (Victorian semi-detached house).

On the other side of the internal wall is the porch, which does not have any damp. Since moving in, we had the front facade of the house lime pointed but the damp has not improved. No other areas have damp like this. The previous owners treated this area for rising damp, but I cannot see how it's getting up so high up the wall?!

It gets worse when raining, but never really dries out except in mid summer with the dehumidifier on.

The front facade is granite with lime pointing. Internal wall is brick and plaster. The inside of the external wall is plasterboard (potentially damp behind but we'd have to take it down to find out).

Any thoughts would be much appreciated.

 

[DampedOut]

Could this be water coming in around the upstairs window above and then the water is moving along a lintel sideways and coming down this way?

 

[DaveG]

Agree with the last post in as much as I’d probably be looking for ingress from above if the watermark is that high up.
Difficult to visualise but when you say this is an internal wall, is that purely because there’s a porch (an additional structure added on) on the other side of it? If so, if the porch is joining up against this wall in some way and lead work is involved I’ve read that it can be quite deceptive in terms of looking sound but having tiny cracks and allowing water to track in so worth a look

 

[Stevers]

Granite is an impermeable rock, so if the stone isn't laid correctly, water can track through a wall quite easily from external defects.

A picture of the outside in this area would be useful.

 

[kernowqueen]

Could this be water coming in around the upstairs window above and then the water is moving along a lintel sideways and coming down this way?

Thanks for your reply, well we've had 3 window fitters come to look:

the first said it's definitely the window seals that will have perished (from the window above the living room) and the window needs to be replaced

the second said it definitely cannot be the window seals because even if they had perished the slate sills are so deep that water would have to be coming in sideways and going uphill for 30cm before tracking down (which isn't the case as it's been drizzling for 2 days and the damp has got worse).

and the third guy said it could be the window seal but he wouldn't want to guarantee it'll fix the problem.

Potentially two very honest window fitters?! But obviously not clear cut and we may need to get a 4th or 5th opinion!

 

[kernowqueen]

Agree with the last post in as much as I’d probably be looking for ingress from above if the watermark is that high up.
Difficult to visualise but when you say this is an internal wall, is that purely because there’s a porch (an additional structure added on) on the other side of it? If so, if the porch is joining up against this wall in some way and lead work is involved I’ve read that it can be quite deceptive in terms of looking sound but having tiny cracks and allowing water to track in so worth a look

Thanks for this. The porch is not an external porch, it's just partitioned as an entranceway. So the corner is a T shape with the front facade being the 'top' of the T, and the partition wall being the vertical line (of which, the left hand side is showing damp, right is not). Hope that helps to picture it better. Sorry haven't got a picture of outside handy and it's raining!

 

[malcolm]

It would be interesting to see a wide shot photo of outside showing the house with an arrow pointing to where the wall is. Looks like the full height of the external wall is wet for some reason and it's trying to dry into the internal wall. It's unusual for damp to go that high up.

 

[kernowqueen]

Granite is an impermeable rock, so if the stone isn't laid correctly, water can track through a wall quite easily from external defects.

A picture of the outside in this area would be useful.

Found a picture of the front!

The partition wall is basically halfway between the front door and bay window.

 

[kernowqueen]

Very roughly where porch/partition wall is.

 

[malcolm]

Roughly where the weed is growing out of the wall? The wall needs to be wet to sustain weeds.

The weed is growing on top of a mystery plinth which will likely be cement. Knocking that cement off will likely help a bit. Though it was probably added for a reason. The concrete path looks like it might be about the same level as interior floor level. Is it? Maybe if the exterior pointing was in cement and caused damp problems the damp people came in and made the interior cement too. That left the wall no chance to expel moisture and water that found it's way under that plinth made the wall wet. Then more water made the wall more wet.

If the exterior has been repointed in lime (the type that doesn't have cement added to it so is breathable) then it should dry in time (year or two) but the water ingress probably wants some thinking.

 

[kernowqueen]

Roughly where the weed is growing out of the wall? The wall needs to be wet to sustain weeds.

The weed is growing on top of a mystery plinth which will likely be cement. Knocking that cement off will likely help a bit. Though it was probably added for a reason. The concrete path looks like it might be about the same level as interior floor level. Is it? Maybe if the exterior pointing was in cement and caused damp problems the damp people came in and made the interior cement too. That left the wall no chance to expel moisture and water that found it's way under that plinth made the wall wet. Then more water made the wall more wet.

If the exterior has been repointed in lime (the type that doesn't have cement added to it so is breathable) then it should dry in time (year or two) but the water ingress probably wants some thinking.

Sorry not sure I follow as there's no weed growing out of the plinth, possibly just looks that way from the photo.

The plinth is now lime - it was cement and yes when the cement was taken off, it was wet behind it. So they rebuilt the plinth in lime and most areas which were slightly damp internally have now dried. It's just this wall, with water ingress during wet weather, that is causing problems now. Thank you for your replies!

 

[kernowqueen]

No weeds growing from the wall either, bit of lichen on the granite but no greenery.

 

[DaveG]

If I had to place my bets I’d say the bay window roof seems the most obvious thing that could bring the moisture in at that level. It looks tidy but it looks the right height to channel water into that area to me. I’ve heard that lead can have the most minuscule of holes or cracks almost invisible to the eye and cause havoc. Not saying it definitely is that but from the picture it looks the most obvious thing to check, double check and then check again!

 

[Richeee]

Hi. New on here, and my lime breathability knowledge is just beginning but have knowledge of more common building in the dpm world.

First off the damp is not proportionate to the rest of the areas. So yes there must be an isolsted problem due to excess water in that area.

If no pipework either side of the partition wall. Drainage or water, including central heating then must be coming from somewhere else.

As suggested previously looking outside the bay window would seem to be the obvious first place to start.
How are the tiles butted up to the stone. I can see flashings over the top. But what about under the slates. Soakers .These are L shaped that go under the slate and then go up the wall. These would prevent any water that gets under the top and side flashings from just going where it wants to either blown in or by natural capillary action being drawn to the stone like a sponge. It is channeled down and away. Are they present.?
It might just be at the lower extremities of the lead the ends are nicely tapped up against the stone allowing water to run down the wall. Would like to see the lead shaped away from the stone if only a few mm's so that the water has a chance to drip off away from the wall you are trying to dry.
Gutter. A little gutter would not go amiss to collect water that is coming off the roof and direct it somewhere away. Not just down over the fascia. Slate over hang seems preety minimal. Need to get water away from the structure. The lead flashing on the rhs would seem to at present let the water run on the facia and stone.
If the lhs is the same....

Would like to see the lead soakers and flashings dripping into a gutter and down a pipe and away from the wall.
This is where i would start. But im a newbie to stone and lime and may be barking up the wrong tree.

 

[Stevers]

That bay window may not be as built and has no soakers and flashing going up the wall, which is something that is not ideal, and worth looking at given that you have a leak .

Looks like you've got plastic gutters, fascias and soffits, so worth checking that the tiles or slates still have a decent overlap to direct the water into the gutters, and not dribble it inside the fascia and down the wall. That's what happened after my father replaced his cast iron ogee guttering with plastic gutters and fascia that stuck out beyond the limited overlap of the plain tiles.